Ultrasonic imaging is an important and cost effective medical diagnostic tool. Ultrasonic spectrum analysis has been used to diagnose and monitor disease in experimental settings. However, ultrasonic techniques which can reliably differentiate among tissues, e.g., between cancerous tissue and non-cancerous tissue, have proven elusive.
It is well established that early detection of cancer is a key element to successful treatment. In the case of prostate cancer, where nearly 180,000 new cases are expected to be detected in 1999 in the United States alone, cancer detection usually requires undergoing a needle biopsy under the guidance oftransrectal ultrasound (TRUS). However, while TRUS can effectively display the outline of the prostate, thus insuring that the biopsy needle is properly directed into the glandular portion of the prostate where cancer generally arises, current TRUS is limited in its ability to define areas within the prostate of high cancer risk. As a result, the person performing the biopsy takes multiple biopsy samples somewhat randomly using the ultrasonically visible anatomic features of the gland as guides in selecting biopsy sites. However, the fact that nearly 30% of patients who are cancer negative in a first biopsy are cancer positive in a second biopsy taken within a one year period, suggests that many cancers are missed by current TRUS guided biopsy. Thus, a vast opportunity exists for improving the techniques used to select the location of the biopsy sites used for the detection of cancer in the prostate.